Astronomy Picture of the Day

   [1]Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                                2021 July 28
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                           Ring Galaxy AM 0644-741
        Image Credit: [3]NASA, [4]ESA, [5]Hubble, [6]HLA; Processing:
                              [7]Jonathan Lodge

   Explanation: The rim of the large blue galaxy at the right is an
   immense ring-like structure 150,000 [8]light years in diameter composed
   of newly formed, extremely bright, massive stars. [9]AM 0644-741 is
   known as a [10]ring galaxy and was caused by an immense galaxy
   collision. When [11]galaxies collide, they pass through each other and
   their individual stars rarely come into contact. The large galaxy's
   ring-like shape is the result of the [12]gravitational disruption
   caused by a small intruder galaxy passing through it. When this
   happens, interstellar gas and dust become compressed, causing a
   [13]wave of star formation to move out from the impact point like a
   ripple across the surface of a pond. Other galaxies in the field of
   view are background galaxies, not interacting with AM 0644-741.
   Foreground spiky stars are within our own Milky Way. But the smaller
   intruder galaxy is caught above and right, near the top of the frame
   taken by the [14]Hubble Space Telescope. Ring galaxy AM 0644-741 lies
   about 300 million light years away [15]toward the southern
   constellation Volans.

              Tomorrow's picture: the flower and the black hole
     __________________________________________________________________

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    Authors & editors: [27]Robert Nemiroff ([28]MTU) & [29]Jerry Bonnell
                                 ([30]UMCP)
          NASA Official: Phillip Newman [31]Specific rights apply.
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                A service of: [33]ASD at [34]NASA / [35]GSFC
                           & [36]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2107/AM0644-741Full.jpg
   3. https://www.nasa.gov/
   4. http://www.esa.int/
   5. https://www.nasa.gov/mission_pages/hubble/main/index.html
   6. https://hla.stsci.edu/
   7. https://www.instagram.com/jjlodge
   8. http://chandra.harvard.edu/photo/cosmic_distance.html
   9. http://adsabs.harvard.edu/abs/1997ApJ...474..686H
  10. https://apod.nasa.gov/apod/ap010612.html
  11. https://apod.nasa.gov/apod/ap150201.html
  12. http://en.wikipedia.org/wiki/Tidal_force
  13. http://astronomy.swin.edu.au/cosmos/D/density+wave+model
  14. https://hubblesite.org/contents/news-releases/2021/news-2021-045
  15. https://hubblesite.org/contents/media/images/2004/15/1520-Image.html
  16. https://apod.nasa.gov/apod/ap210727.html
  17. https://apod.nasa.gov/apod/archivepix.html
  18. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  19. https://apod.nasa.gov/apod/lib/aptree.html
  20. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  21. https://apod.nasa.gov/apod/calendar/allyears.html
  22. https://apod.nasa.gov/apod.rss
  23. https://apod.nasa.gov/apod/lib/edlinks.html
  24. https://apod.nasa.gov/apod/lib/about_apod.html
  25. http://asterisk.apod.com/discuss_apod.php?date=210728
  26. https://apod.nasa.gov/apod/ap210729.html
  27. http://www.phy.mtu.edu/faculty/Nemiroff.html
  28. http://www.phy.mtu.edu/
  29. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  30. http://www.astro.umd.edu/
  31. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  32. https://www.nasa.gov/about/highlights/HP_Privacy.html
  33. https://astrophysics.gsfc.nasa.gov/
  34. https://www.nasa.gov/
  35. https://www.nasa.gov/centers/goddard/
  36. http://www.mtu.edu/